I think [here](https://searchfox.org/comm-central/rev/722c4715e7cb79068c8df97ba6d7cf968413f23a/mailnews/search/src/nsMsgSearchSession.cpp#517) would be a good place to check if we're shutting down and stop if we are.
Bug 1934491 Comment 1 Edit History
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I think [here](https://searchfox.org/comm-central/rev/722c4715e7cb79068c8df97ba6d7cf968413f23a/mailnews/search/src/nsMsgSearchSession.cpp#391) would be a good place to check if we're shutting down and stop if we are.